Conventionally, benzobisthiazole compounds attract attention as a compound used for an organic thin film transistor (organic TFT), an organic electroluminescence device (organic EL device), or an organic thin film photovoltaic cell, and various derivatives in which the main skeleton is benzobis(thiadiazole) are studied and developed vigorously.
A benzobis(thiadiazole) compound into which a strong electron-withdrawing group is introduced in order to improve the mobility of hole and electron, or the stability in the atmosphere, in particular, is proposed. For example, Non Patent Literature 1 and Non Patent Literature 2 disclose a compound in which trifluoromethylphenyl group is bound to benzobis(thiadiazole) via thienylene group (hereinafter, also referred to as “FPTBBT”). The compound has a mobility improved by the introduction of trifluoromethylphenyl group which is a strong electron-withdrawing group.
Patent Literature 1 also discloses a benzobisthiadiazole compound as an n-type organic semiconductor material, and the compound synthesized herein is 4,8-bis[3,5-bis(trifluoromethyl)phenyl]benzo[1,2-c;4,5-c′]bis[1,2,5]thiadiazole only. Additionally, although the result of the measurement of cyclic voltammetry (CV) of 4,8-bis[3,5-bis(trifluoromethyl)phenyl]benzo[1,2-c;4,5-c′]bis[1,2,5]thiadiazole is described herein, a device such as a thin film transistor (TFT) was not produced with the compound and was not evaluated for the properties, and therefore it is unclear whether the compound has adequate properties as an organic semiconductor material. In addition, no mention is made of the solubility in Patent Literature 1.
Meanwhile, it is generally known that a compound having a strong electron-withdrawing group introduced into thiophene ring has an improved stability or mobility of electron, although the compound is not a compound in which the main skeleton is benzobis(thiadiazole). (See, for example, Patent Literature 2.)
Moreover, Patent Literature 3, which was published on Sep. 26, 2013, discloses a benzobis(thiadiazole) derivative which is soluble in an organic solvent, and also discloses organic electronic devices comprising the benzobis(thiadiazole) derivative, including an organic thin film transistor.